Celticecis oviformis

The spherical stem galls are diagnostic: they are hard, woody, and nearly perfectly round, attached directly to twigs and small branches of hackberry. Distinguished from other Celticecis species by gall location (stems vs. leaves) and shape (spherical vs. irregular or pouch-like). Celticecis capsularis forms smaller, more elongate leaf petiole galls; Celticecis celtiphyllia induces irregular blister galls on leaf blades. The spherical stem gall is unique to C. oviformis among North American hackberry gall midges.

Associated with hackberry trees in deciduous woodlands, riparian forests, urban plantings, and shelterbelts. Galls have been observed on both native and ornamental Celtis species. The midge is tied to the presence of its host plant rather than specific habitat conditions.

Documented across eastern and central North America, from the Great Plains to the Atlantic coast, and from the Great Lakes region south to Texas and Florida. Records correspond with the range of hackberry species, particularly Celtis occidentalis and Celtis laevigata.

Adult emergence timing is poorly documented; galls are visible year-round. Larvae are present within galls through winter. Gall initiation on new growth likely occurs in spring, with mature galls persisting for one to several years.

Larvae feed on nutritive tissue within the gall, induced by the midge's chemical manipulation of host plant cells. The specific nutritional relationship has not been characterized in detail.

• Celtis occidentalis - gall induction on stemsprimary host
• Celtis laevigata - gall induction on stemssouthern records

Induces gall formation on hackberry stems; larvae develop within gall tissue through summer and overwinter. Pupation occurs within the gall. Adults emerge through exit holes, leaving small circular openings in the gall wall. The complete life cycle duration and number of generations per year are not established.

Adults are weak fliers, active for brief periods. The species is known primarily through its gall induction; direct behavioral observations of adults are scarce. Larvae are sedentary, developing within the protected gall chamber.

Galls provide microhabitat for inquilines and parasitoids, though specific associates of C. oviformis are not well documented. The galls represent a minor sink of host plant resources but do not typically cause significant tree mortality.

Galls are conspicuous on ornamental hackberries and may be noticed by arborists and gardeners, but cause no significant economic damage. Occasionally used in educational contexts to illustrate plant-insect interactions. The species is not a pest of agricultural or forestry significance.

• Celticecis capsularisForms smaller, elongate-oval galls on leaf petioles rather than spherical stem galls.
• Celticecis celtiphylliaInduces irregular, pouch-like blister galls on leaf blades, not hard spherical stem galls.
• Pachypsylla species (jumping plant lice)Form various hackberry galls but belong to Hemiptera; galls are structurally different and adults are psyllids, not midges.

• gall midge
• hackberry
• Celtis
• stem gall
• Cecidomyiidae
• North America

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life